Magnetite Veins in the Pyritic Ore Bodies in the Yanahara Mine

Abstract

Some magnetite veins exist in the pyritic ore bodies in the Yanahara mine. They are several centimeters to several decimeters thick and are composed chiefly of magnetite, calcite, chlorite, biotite and pyrrhotite. The occurrence and paragenesis of the veins suggest formation by reaction between pyrite and a hydrothermal solution which was introduced along fractures in the preexisting pyritic ore bodies. The solution might be the residue of a Cretaceous granite magma.